This blog discusses current weather, weather prediction, climate issues, and other topics

Thursday, August 6, 2015

Moisture Returns

Could August end up wetter than normal?

As noted in my previous blog, the atmospheric circulation has changed substantially, with the replacement of high pressure with troughing over the eastern Pacific. The latest runs are trending wetter and wetter. The latest forecasts of the NOAA CFSv2 forecast for the next two weeks indicate wetter conditions than normal.

But the CFS model is very coarse and can't get the details of Northwest weather. So let's look at the latest UW WRF forecast. Over the next 72 h, southern BC and Vancouver Island will get quite wet, with over an inch of precipitation in places, but only light right over western Washington.

During the next 72 h, western WA and Oregon get modest amount, particularly over the Cascades.

But it will be the next 48 hours, during the middle of next week, that will really get wet, with even eastern WA getting into the action. Obviously, this is relatively far out in time, but other models are in agreement with this solution.

So ironically, during one of the climatologically driest times of the year, substantial precipitation will be falling. Importantly, this period will have a hugely beneficial effect on our water situation, reducing the need for irrigation and partly filling our reservoirs.

17 comments:

(This is my comment about watering lawns that I have been holding on to for a week or two. A couple of your readers went back and forth about saving water a little while ago and I wanted to put my two cents in finally).

In this hot dry summer, I have managed to keep a green lawn for just $100 of water: I usually let my lawn go dormant in the summer but, amazingly, I have a nice lawn this year.The 3000 gallons that usually go in a kid pool went on the lawn each morning or evening--just 50 gallons at a time--enough to keep it fairly green but not really growing. Our lawn is shaded for half the day which helps a great deal, and we have had a couple of PSCZ rains in the past week or so. The rain hasn't done much of anything for the ground an inch or two down, but it has been good for the lawn--both the showers and the cool weather have helped. I even had to mow the other day for the first time this past month. Now, my frugal watering wouldn't have worked in all day full sun, and our lawn is only a small fraction of our lot, mostly we have trees and ferns--but in the part of the garden where we like to have a green patch this was a fun experiment: Shallow watering does work for some lawns, deep watering would have been a waste. And on that note--for a few things that do need some moisture down deep, I have this nozzle that sprays a sharp forceful stream, I inject water past the mulch and into the soil in those areas where I want to get some water down in the soil. I did this for my bamboo and a few rhodies.

I hope you are right about the rain! It seems like we've had a "rain mirage" effect in the weather forecasts lately, much like the snow mirage in winter: they keep forecasting rain a few hours to a few days ahead, then it vanishes (and does not fall from the sky) as the time gets closer. What's going on with that?

Molly, I've noticed that tends to happen every summer as the season transition begins. Essentially we get a series of false starts before the rains begin. I view it a bit like the atmosphere destabilizing and it's a gradual process. Early in the season, it seems like the dry weather has "momentum" until the moisture levels build enough pressure to be consistent.

This summer has been one for the record books, that's for sure. Sitting here today with it being 68F at noon under crystal blues skies has made the last couple of months seem like a bad dream finally. The next couple of weeks looks to be awesome.

Unreal how dry it has been this summer. Yeah, native plants are pretty drought tolerant for the summer months, but this year has been so, so dry. We have had .16" of rain here at the house since June 1. Going back to May 1st shows only .62" of rain and even going back to April 1st only shows 2.67" of rain. That amounts to a normal April amount of rain over four and half months and then the equivalent of nothing over the last 3.5 months.

Interesting. The forecasts Cliff references are rather different (wholly different, in fact) than that of Weather Underground. It may well be that the cooler/wetter prediction is, as Molly suggested above, but a mirage.

Found this blog from down south. Hope you send some of that wet stuff down here in Cali. I'm tired and need a little break from being on the firelines for many days now. And yes our fire season, at least in California is starting earlier but also lasting longer.

Argh, yep - I've been longing for rain and have been checking the forecast semi-obsessively. The 50% chance of rain on several different days now has receded to a 20% and now a 10%, and "cloudiness" instead of "showers." Don't mirage us, rain! Do I have to go wash the car to make this happen or what?

Colleen-Yes - saw the same here. All of the forecasts that were calling for clouds and low 70s Tues - Thurs have now gone 180 and we're back with sunshine and mid 80's again. Here's hoping Cliff is correct!

I have just moved here from Washington DC. DC had 12 inches of rain (twelve!) in June alone; to date so far, DC has seen 31.97". Moving to Seattle I never thought I'd say this: I really miss rain, and the radiantly green grass of DC. I have a photo I took the day I left (June 30); I wish I could post it so you could see the glorious green I left behind, and I was so stunned to see the lawns here completely dead, burnt out beyond recognition. Does the grass go brown every summer here?

I have been here for nearly 1.5 months, and have yet to see any rain at all. There was drizzle once or twice, not even enough to open an umbrella.

Literally EVERY PERSON who I told in DC that I was moving to Seattle immediately responded with, "that's going to be tough - it rains INCESSANTLY out there." I'd like all of those folks to come and see how dead wrong they were!